Those people strapped into those chairs look like they were trepanated. That is had a hole drilled into their skulls. It was used as a “medical practice” a long time ago to release demons and spirits that they thought caused headaches and other ailments. But it was also thought to allow communication with the divine (as there was no longer a barrier/skull in the way) One of the issues that come from opening the skull is infection and inflammation (swelling) of the brain. That also might be why they are looking for more brain fluid as the procedure might leave theirs missing or in a constant state of draining.